In existing electronic pre-press systems, images to be printed by offset printing are scanned from photographic sources and digitized. The digitized images are then transmitted to a raster image processor (RIP) for half-tone screening and image rasterization. The rasterized image is then transmitted to an imagesetter for recording of the image onto a medium. Such recording is referred to as imaging or imagesetting, and may for example be performed by photographic recording of an image onto a photosensitive medium such as paper, film, or printing plates. A medium which has had an image recorded onto it by an imagesetter is referred to as imaged medium.
Existing pre-press systems typically include independent functional units for recording images and for subsequent processing. A typical photographic imagesetter operates to record a predefined image onto a medium, for example by first mounting the medium onto the internal surface of a drum (i.e. in an internal drum imagesetter), then exposing the medium with a laser beam via a rotatable, optically reflective element mounted on the interior of the drum. The medium typically may be supplied as a web or as a cut sheet.
Subsequent to imaging, the imaged medium is passed to a development/finishing processor, where the medium will undergo chemical processing for photographically developing, fixing and washing. Alternatively, if the image was burned into the media by a laser, then mechanical finishing would occur in the processor. If the media was supplied by a continuous web, each sheet of exposed media is cut prior to entry into the processor.
Early pre-press systems used off-line development processors. In such early systems, imaged media was collected onto a take up cassette connected to an output of the imagesetter, and then manually transported to the off-line processor. More recent systems have coupled the imagesetter to an on-line processor, which inputs the imaged media directly, automatically from the imagesetter.
A significant drawback of existing systems using on-line processors results from the different processing speeds of the imagesetter and the processor. This and other problems were addressed in U.S. Pat. No. 5,769,301 issued Jun. 23, 1998 to Hebert et al. herein incorporated by reference in its entirety for supplemental background information which is not essential but is helpful in appreciating the applications of the present invention. Hebert et al. discloses a media transport bridge for use in transporting and buffering imaged media between an imagesetter and a processor. When a medium is output from the imagesetter, it is transferred to a bridge mechanism between the imagesetter and the processor. The bridge mechanism holds the medium for a predetermined period of time while waiting for the processor to become available. When the processor's availability is detected, the medium is transferred from the bridge to the processor, and the bridge thereafter becomes available to store a second sheet of media from the imagesetter. However, during the time while the bridge is waiting for the processor to accept the second sheet of media, the imagesetter may have to be stalled, waiting for the bridge to become available. Such stalling of the imagesetter potentially causes an unacceptable reduction in overall media throughput. Moreover, existing bridge mechanisms often have high profiles, resulting in undesirably large form factors for products in which they are included.